AbstractSuperluminous supernovae (SLSNe) are an emerging class of SNe that exhibit luminosities exceeding those of SN Ia by an order of magnitude and have light curves with characteristic timescales of hundreds of days. Here we present observations of the host galaxies of 21 SLSNe observed with the Hubble Space Telescope, and show that their ultraviolet (UV) and near-infrared (nIR) luminosities and sizes and very different from those of the hosts of other core collapse events, with significant implications for their progenitors.